A data storage device with improved data storage densities, coupled with lower hard error and write-inhibit events is described. A feed-forward write inhibit (FFWI) method enables data tracks to be written more densely. Alternatively, the FFWI method may reduce the hard error and write inhibit events to improve data storage performance. A concept of virtual tracks enables the FFWI method to be applied to the writing of circular data tracks with non-circular servo tracks, or to the writing of non-circular data tracks with PES data from circular servo tracks—in both cases, improvements to performance and/or storage densities are enabled. The FFWI method may also be applied to the case of both non-circular servo and data tracks.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A data storage device comprising: a rotating data storage medium, comprising: data tracks; servo data sectors, comprising servo burst patterns; a read/write head assembly, comprising a read head configured to read data from the rotating data storage medium, and a write head configured to write data to the rotating data storage medium; and a controller for controlling the position of the read/write head assembly relative to the rotating data storage medium, wherein the controller is configured to: receive positional error signals from the read head generated when the read head passes over a servo burst pattern; store the positional error signals generated from all servo burst patterns around a track on the rotating data storage medium as data is being written by the write head to the rotating data storage medium; calculate a fixed first write inhibit limit on a first side of the track being written, wherein the fixed first write inhibit limit is located on the opposite side of the track being written from a neighboring track, and wherein the distance between the track being written and the first write inhibit limit has a fixed and predetermined value; calculate a variable second write inhibit limit for the track being written, the variable second write inhibit limit is variable with respect a track center of the neighboring track, wherein the second write inhibit limit is on the opposite side of the track being written from the first write inhibit limit, and wherein the distance of the second write inhibit from the center of the neighboring track has a fixed and pre-determined value; and determine whether the positional error signal is between by the two write inhibit limits, wherein: if the positional error signal is between the first and second write inhibit limits, then enable writing on the rotating data storage medium; or if the positional error signal is not between the first and second write inhibit limits, then inhibit writing on the rotating data storage medium.
2. The data storage device as in claim 1 , wherein the variable second write inhibit limit comprises a component proportional to the fixed first write inhibit limit.
3. The data storage device as in claim 2 , wherein the proportionality constant preferably ranges from minus 1.0 to minus 2.2.
4. The data storage device as in claim 2 , wherein the proportionality constant more preferably ranges from minus 1.2 to minus 1.7.
5. The data storage device as in claim 1 , wherein the second write inhibit limit comprises a component proportional to the positional error signal of a neighboring track.
6. The data storage device as in claim 5 , where the constant of proportionality is one.
7. The data storage device as in claim 1 , wherein the controller is further configured to fit a function to the sequence of positional error signals around the track.
8. The data storage device as in claim 7 , wherein the function is a polynomial.
9. The data storage device as in claim 7 , wherein the function is a harmonic of a single rotation of the rotating data storage medium.
10. The data storage device as in claim 9 , wherein the harmonic is a first-harmonic of a single rotation of the rotating data storage medium.
11. The data storage device as in claim 7 , wherein the controller is further configured to compute the derivative of the function with respect to rotation of the rotating data storage medium.
12. The data storage device as in claim 11 , wherein the controller is further configured to compute a required radial correction to the track position based on the derivative of the function and a predetermined minimum track spacing.
13. The data storage device as in claim 12 , wherein the controller is further configured to adjust the first and second write inhibit limits based on the required radial correction to the track position.
14. A method for varying write inhibit limits in a data storage device comprising: a rotating data storage medium, comprising: data tracks; servo data sectors, comprising servo burst patterns; a read/write head assembly, comprising a read head configured to read data from the rotating data storage medium, and a write head configured to write data to the rotating data storage medium; and a controller for controlling the position of the read/write head assembly relative to the rotating data storage medium, wherein the controller is configured to receive positional error signals from the read head generated when the read head passes over a servo burst pattern; the method comprising: writing a first data track on the rotating data storage medium subject to write inhibit limitations based on predetermined fixed write inhibit limits on both sides of the first data track; saving the positional error signals generated during writing of the first data track; and writing a second data track, neighboring to the first data track, subject to write inhibit limitations based on a fixed first write inhibit limit on the side of the second data track opposite from the first data track, and a variable second write inhibit limit on the side of the second data track adjacent to the first data track, the variable second write inhibit limit is variable with respect a track center of a neighboring track, wherein the distance of the variable second write inhibit limit from the center of the first data track has a fixed and pre-determined value; wherein if the positional error signal is between the first and second write inhibit limits, then enable writing of the second data track; or if the positional error signal is not between the first and second write inhibit limits, then inhibit writing of the second data track.
15. The method as in claim 14 , wherein the variable second write inhibit limit comprises a component proportional to the fixed first write inhibit limit.
16. The method as in claim 15 , wherein the proportionality constant preferably ranges from minus 1.0 to minus 2.2.
17. The method as in claim 15 , wherein the data storage device further comprises a vibration sensor, configured to convey a vibration level signal to the controller; and wherein the proportionality constant has a first value when the vibration level indicates non-vibrational and non-shock operating conditions, and the proportionality constant has a second value when the vibration level signal indicates vibrational or shock operating conditions.
18. The method as in claim 15 , wherein the proportionality constant has a first value when writing temporary cache regions of the rotating data storage medium, and the proportionality constant has a second value when writing final home or destination regions.
19. The method as in claim 14 , wherein the variable second write inhibit limit comprises a component proportional to the positional error signal of the first track.
20. The method as in claim 19 , where the constant of proportionality is one.
21. The method as in claim 14 , wherein a function is fitted to the sequence of positional error signals around the track.
22. The method as in claim 21 , wherein the function is a polynomial.
23. The method as in claim 21 , wherein the function is a harmonic of a single rotation of the rotating data storage medium.
24. The method as in claim 23 , wherein the harmonic is a first-harmonic of a single rotation of the rotating data storage medium.
25. The method as in claim 21 , wherein the derivative of the function with respect to rotation of the rotating data storage medium is computed.
26. The method as in claim 25 , wherein a required radial correction to the track position is computed, based on the derivative of the function and a predetermined minimum track spacing.
27. The method as in claim 26 , wherein the first and second write inhibit limits are adjusted based on the required radial correction to the track position.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
August 24, 2012
February 10, 2015
Browse 5M+ US patents with plain-English claim translations and AI-generated analysis.